Posted by Henry P on .
The area of a circle is given by the expression pi(16x^2  40x + 25) .
a) What is the diameter of the circle?
b) What is its circumference?

Math 
bobpursley,
area= PI (4x5)^2
but area= PI r^2
so r= 4x5
diameter= 2*r
circumference= 2PI*r